1. Technical Field
The present invention relates to a digitizer.
2. Description of the Related Art
In accordance with the growth of computers using a digital technology, devices assisting computers have also been developed, and personal computers, portable transmitters and other personal information processors execute processing of text and graphics using a variety of input devices such as a keyboard and a mouse.
While the rapid advancement of an information-oriented society has widened the use of computers more and more, it is difficult to efficiently operate products using only a keyboard and a mouse currently serving as an input device. Therefore, the necessity for a device that is simple, has minimum malfunction, and is capable of easily inputting information has increased.
In addition, current techniques for input devices have progressed toward techniques related to high reliability, durability, innovation, designing and processing beyond the level of satisfying general functions. To this end, an electromagnetic induction type digitizer has been developed as an input device capable of inputting information such as text, graphics, or the like.
An example of an input device capable of performing a function similar to the electromagnetic induction type digitizer may include a capacitive type touch screen. However, the capacitive type touch screen cannot accurately sense coordinates and cannot also recognize writing pressure, as compared to the electromagnetic induction type digitizer. Therefore, the electromagnetic induction type digitizer has better precision or accuracy than the capacitive type touch screen.
However, like the digitizer described in the follow prior art document, the digitizer according to the prior art makes a direction of a magnetic line of force different along a length direction applied to a sensing coil along a length direction of the sensing coil due to current applied to a driving coil. In other words, the sensing coil is divided into an area that faces the driving coil and an area that does not face the driving coil while intersecting the driving coil. In this case, a direction of the magnetic line of force applied to the area that faces the driving coil and a direction of the magnetic line of force applied to the area that does not face the driving coil are opposite to each other.
As a result, the digitizer according to the prior art causes a phenomenon in that current induced to the sensing coil is offset around the coil to which the magnetic line of force is applied in directions opposite to each other.
In the digitizer structure, in order to precisely detect touched coordinates of an input unit such as an electronic pen, and the like, voltage induced to the sensing coil does not need to have a sufficient value.
However, the digitizer according to the prior art does not induce sufficient voltage to the sensing coil due to the forgoing offset phenomenon.